The role of molybdenum as a trace element in humans is an important one; it is present in the active site in the "oxotransferase" enzymes sulfite oxidase, xanthine dehydrogenase, aldehyde transferase as the molybdenum co-factor which is necessary for these enzymes to operate. Children who have low levels of functioning sulfite oxidase and xanthine dehydrogenase have been found to exhibit mental retardation, neurological abnormalities, displaced ocular lenses and retarded physical development. In this project, the synthesis and characterization of a series of analogous compounds, MoS2-nOn(mu-S)2Ru(ii)Lx(Lx=2, 2'-bipyridine (bipy) or 2,6-bis(2'-pyridyl)pyridine (terpy) + H2O) will be performed. In this series of compounds, the molybdenum atom will have coordination spheres similar to those proposed for the active sites of xanthine dehydrogenase and sulfite oxidase and will be bonded to one electron redox active ruthenium polypyridyl complexes by bridging sulfide groups. Methods of characterization will include investigations of the electronic absorption spectrum, electrochemistry and chemical reactivity of these complexes. The nature of the oxidation and reduction products will be investigated through in situ electrolysis in optical absorption and EPR spectroscopic cells. The long term objectives are to investigate (a) the scope of the reactivity of such systems and (b) the viability of covalently attached transition metal complexes as simple redox reservoirs in model systems.